This invention relates to a system for preventing arcing between female contacts of an electric plug and male contacts of an electrically operated device requiring high current.
The plug is a female member containing two high current contacts and one low current contact. The male receptacle has two high current prongs and one low current prong connected to a solid state switch via a gate control.
Arcing generally occurs between contacts of a plug and socket of an electric appliance when the plug is removed from the socket while the current is turned on. This arcing tends to burn the terminals and can be a fire hazard.
Thus, it is usually desirable and sometimes necessary to insure that the electric current to a two-part electrical connector is broken whenever the two parts of the connector are disengaged from each other. There are a number of ways in which an interlock involving the connector can be provided to achieve such disengagement. For example, the connector may be provided with mating plug and socket elements in addition to those required to establish the desired electrical current through the connector. A break in the engagement between the additional plug and socket elements is used to indicate the disengagement of the connector parts carrying the current. Also, a microswitch may be mounted on a connector to respond to mechanical disengagement of the parts of the connector. In either of the above cases, there are practical problems of insuring that the supply of electricity to the connector is broken without undue delay. Avoiding undue delay in operation of the interlock is important, particularly in the case of high voltages, otherwise arcing may occur within the connector during disengagement.
McDonald, et al. U.S. Pat. No. 4,044,208, issued Aug. 23, 1977 disclose a two-part electrical connector wherein the two parts are engageable in a mating relationship to establish electrical interconnection through the connector. An electrical conductor element is carried by one of the two parts and two electrical contact elements are mounted with the other of the two parts to abut the said conductor element so the two contact elements are thereby bridged electrically by the conductor element when the parts are in mating relationship. The electrical connector has an electrically conductive ring on the male portion which contacts two pins on opposite sides of the female socket to complete a circuit and activate an interlock switch. The contact does not occur until the two major contacts are made and, conversely, is broken prior to full disconnection of the male and female parts. McDonald, et al. disclose use of the connector and interlock in the supply of extra-high tension to a cathode ray tube.
The above described interlocks and connectors are, in general, costly.
There are no two-part electrical connector and interlocks disclosed which utilize a female plug, a male socket and a solid-state switch with a gate drive wherein the configuration of the contacts on the plug causes the removal of the gate drive before removal of power from the high current contacts when the alternating current cord is removed.
It is an object of this invention to provide a structurally simple, economical to operate, connector interlock system which prevents arcing.
It is another object of this invention to provide a two-part connector-interlock system comprising a male socket, female plug and solid-state switch.